Along with the recent development of the so-called information-oriented society, electronic apparatuses, such as personal computers and PDA (Personal Digital Assistants), have been used widely. With the spread of such electronic apparatuses, portable apparatuses that can be used in offices as well as outdoors have been demanded, and these apparatuses are requested to be made small in size and light in weight. Liquid crystal display devices are widely used as one of the means for satisfying such requests. Liquid crystal display devices include not only the technology that makes the apparatuses small in size and light in weight but also the technology that is indispensable to reduce the power consumption in portable electronic apparatuses driven by batteries.
Liquid crystal display devices are broadly classified into a reflection type and a transmission type. The reflection type is configured so that light rays incident from the front face of a liquid crystal panel are reflected by the rear face of the liquid crystal panel, and an image is made visible using the reflected light; the transmission type is configured so that an image is made visible using the transmitted light from a light source (backlight) provided on the rear face of the liquid crystal panel. The reflection type has poor visibility because the amount of the reflected light varies depending on environmental conditions; hence, transmission type color liquid crystal display devices using color filters are generally used as the display devices of personal computers for carrying out full-color display in particular.
As the color liquid crystal display devices, active-driven liquid crystal display devices using switching elements, such as TFTs (Thin Film Transistors), are widely used at present. Although the TFT-driven type liquid crystal display devices are relatively high in display quality, they require a high-intensity backlight to obtain high screen brightness because the light transmittance of the liquid crystal panel thereof is low, several percent. For this reason, the power consumption increases due to use of the backlight. Furthermore, the liquid crystal is low in responsivity to an electric field and has a problem of low speed of response, that is, a problem that the speed of response is low in halftones, in particular. Moreover, because color display is carried out using color filters, a single pixel must be formed of three sub-pixels; hence, it is difficult to obtain a high-resolution display, and the purity of the displayed colors is not sufficient.
In order to solve these problems, the present inventors have developed field-sequential type liquid crystal display devices (see, for example, T. Yoshihara et al., ILCC 98, P1-074, 1998; T. Yoshihara et al., AM-LCD '99 Digest of Technical Papers, p. 185, 1999; and T. Yoshihara et al., SID '00 Digest of Technical Papers, p. 1176, 2000).
Because the field-sequential type liquid crystal display device does not require sub-pixels, the liquid crystal display device can easily attain higher resolution display in comparison with the color-filter type liquid crystal display device; furthermore, because the field-sequential type liquid crystal display device can directly use the colors emitted from the light source without using color filters, the displayed colors are excellent in purity. Moreover, because the light utilization efficiency is high, the liquid crystal display device has the advantage of low power consumption. However, high-speed responsiveness (2 ms or less) is essential for the liquid crystal in order to realize such a field-sequential type liquid crystal display device.
Hence, in order to provide a field-sequential type liquid crystal display device having the above-mentioned excellent advantages or to increase the response speed of a color-filter type liquid crystal display device, the present inventors are engaged in research and development to drive a liquid crystal, such as a ferroelectric liquid crystal, that has spontaneous polarization and can be expected to achieve high response speed, 100 to 1000 times the conventional response speed, using switching elements, such as TFTs (for example, Japanese Patent Application Laid-Open No. 11-119189/1999).
In the ferroelectric liquid crystal having spontaneous polarization, liquid crystal molecules are arranged in nearly parallel with the substrate, and the direction of the long axis of the liquid crystal molecules is changed by voltage application. A liquid crystal panel in which the ferroelectric liquid crystal is sandwiched between two polarization plates, the polarization axes of which are orthogonal to each other, and the intensity of the transmitted light is changed using birefringence caused by the change in the direction of the long axis of the liquid crystal molecules.
In recent years, the request for three-dimensional image display is intensified, and a liquid crystal display device that carries out three-dimensional image display using multiple liquid crystal panels stacked has been proposed (see, for example, M. Date et al., IDW '03 Proceedings of The 10th International Display Workshops, p. 1409, 2003).